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1.
Ribulose-1,5-bisphosphate regeneration limitation in rice leaf photosynthetic acclimation to elevated CO2 总被引:1,自引:0,他引:1
Dao-Yun Zhang Gen-Yun Chen Zi-Ying Gong Juan Chen Zhen-Hua Yong Jian-Guo Zhu Da-Quan Xu 《Plant science》2008,175(3):348-355
Our previous study has demonstrated that both RuBP carboxylation limitation and RuBP regeneration limitation exist simultaneously in rice grown under free-air CO2 enrichment (FACE, about 200 μmol mol−1 above the ambient air CO2 concentration) conditions [G.-Y. Chen, Z.-H. Yong, Y. Liao, D.-Y. Zhang, Y. Chen, H.-B. Zhang, J. Chen, J.-G. Zhu, D.-Q. Xu, Photosynthetic acclimation in rice leaves to free-air CO2 enrichment related to both ribulose-1,5-bisphosphate carboxylase limitation and ribulose-1,5-bisphosphate regeneration limitation. Plant Cell Physiol. 46 (2005) 1036–1045]. To explore the mechanism for forming of RuBP regeneration limitation, we conducted the gas exchange measurements and some biochemical analyses in FACE-treated and ambient rice plants. Net CO2 assimilation rate (Anet) in FACE leaves was remarkably lower than that in ambient leaves when measured at the same CO2 concentration, indicating that photosynthetic acclimation to elevated CO2 occurred. In the meantime the maximum electron transport rate (ETR) (Jmax), maximum carboxylation rate (Vcmax) in vivo, and RuBP contents decreased significantly in FACE leaves. The whole chain electron transport rate and photophosphorylation rate reduced significantly while ETR of photosystem II (PSII) did not significantly decrease and ETR of photosystem I (PSI) was significantly increased in the chloroplasts from FACE leaves. Further, the amount of cytochrome (Cyt) f protein, a key component localized between PSII and PSI, was remarkably declined in FACE leaves. It appears that during photosynthetic acclimation the decline in the Cyt f amount is an important cause for the decreased RuBP regeneration capacity by decreasing the whole chain electron transport in FACE leaves. 相似文献
2.
Net photosynthetic rate (P
N) measured at the same CO2 concentration, the maximum in vivo carboxylation rate, and contents of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (RuBPCO) and RuBPCO activase were
significantly decreased, but the maximum in vivo electron transport rate and RuBP content had no significant change in CO2-enriched [EC, about 200 μmol mol−1 above the ambient CO2 concentration (AC)] wheat leaves compared with those in AC grown wheat leaves. Hence photosynthetic acclimation in wheat
leaves to EC is largely due to RuBP carboxylation limitation. 相似文献
3.
Involvement of nitrogen and cytokinins in photosynthetic acclimation to elevated CO2 of spring wheat
Diego Gutiérrez Rosa Morcuende Alejandro Del Pozo Rafael Martínez-Carrasco Pilar Pérez 《Journal of plant physiology》2013
Acclimation of photosynthetic capacity to elevated CO2 involves a decrease of the leaf Rubisco content. In the present study, it was hypothesized that nitrogen uptake and partitioning within the leaf and among different aboveground organs affects the down-regulation of Rubisco. Given the interdependence of nitrogen and cytokinin signals at the whole plant level, it is also proposed that cytokinins affect the nitrogen economy of plants under elevated CO2, and therefore the acclimatory responses. Spring wheat received varying levels of nitrogen and cytokinin in field chambers with ambient (370 μmol mol−1) or elevated (700 μmol mol−1) atmospheric CO2. Gas exchange, Rubisco, soluble protein and nitrogen contents were determined in the top three leaves in the canopy, together with total nitrogen contents per shoot. Growth in elevated CO2 induced decreases in photosynthetic capacity only when nitrogen supply was low. However, the leaf contents of Rubisco, soluble protein and total nitrogen on an area basis declined in elevated CO2 regardless of nitrogen supply. Total nitrogen in the shoot was no lower in elevated than ambient CO2, but the fraction of this nitrogen located in flag and penultimate leaves was lower in elevated CO2. Decreased Rubisco: chlorophyll ratios accompanied losses of leaf Rubisco with CO2 enrichment. Cytokinin applications increased nitrogen content in all leaves and nitrogen allocation to senescing leaves, but decreased Rubisco contents in flag leaves at anthesis and in all leaves 20 days later, together with the amount of Rubisco relative to soluble protein in all leaves at both growth stages. The results suggest that down regulation of Rubisco in leaves at elevated CO2 is linked with decreased allocation of nitrogen to the younger leaves and that cytokinins cause a fractional decrease of Rubisco and therefore do not alleviate acclimation to elevated CO2. 相似文献
4.
不同氮源下生长的柚树叶片光合参数对高浓度CO2驯化作用的比较 总被引:4,自引:3,他引:4
比较研究了在不同形式氮源下生长柚树叶片光合对高浓度 CO2 驯化过程中有关参数变化。植株生长在人工混成土壤中 ,分别浇灌含有 2 mmol L- 1N的 NO- 3 - N,NH+ 4 - N和 NH4 NO3- N溶液。空气 CO2 增高处理时向生长植株的开顶透明罩中通入 74.4Pa CO2 ,以空气 CO2 生长的植株为对照。利用 CI- 30 1 ( CID,Inc) CO2 气体交换系统测定叶片光合速率和通过光合作用相关响应曲线计算光合参数。结果表明 ,在 CO2分压倍增下 ,NO- 3 - N生长植株光饱和光合速率较大气 CO2 分压下的高。而生长在 NH+ 4 - N和 NH4 NO3- N的植株光合速率与大气 CO2 分压下的相近 ,表现对高 CO2 的驯化。在空气 CO2 倍增下无论供给何种形式氮源并不影响Γ* ,但可增高 Rd( P<0 .0 5 )。 CO2 分压倍增下供给 NO- 3 - N植株的 Vcmax和 Jmax较大气分压相应的植株高 ,而 NH+ 4 - N和 NH4 NO3- N植株则与大气 CO2分压的相应植株相似 ( P>0 .0 5 )。无论供给何种形式氮源 ,生长在空气 CO2 分压倍增下不改变叶片单位面积干重 ,叶绿素含量和叶片中氮在 Rubisco、生物能学组分和捕光色素复合体组分的分配系数 ;但能改变叶片中氮含量。植物对高 CO2 的驯化可能受到不同形式氮利用性的影响 ,在对高 CO2 驯化过程亦反映叶片中氮在不同光合功能组分 相似文献
5.
高大气CO2浓度下小麦旗叶光合能量利用对氮素和光强的响应 总被引:2,自引:0,他引:2
采用开顶式气室盆栽培养小麦,设计2个大气CO2浓度、2个光照强度和2个氮水平的组合处理,通过测定小麦叶片光合速率-胞间CO2浓度响应曲线和叶绿素荧光参数,来测算小麦叶片光化学速率、光合电子传递速率以及叶绿体磷酸丙糖利用效率(TPU)等参数,研究施氮量和光强对高大气CO2浓度下小麦旗叶光合能量传递与分配的影响,以阐明全球气候变化下植物光合能量分配对光合作用适应性下调的作用机制及其氮素调控。结果表明,大气CO2浓度升高后小麦叶片的光呼吸电子传递速率(J0)和Rubisco氧化速率(V0)显著下降;光合电子流的光化学传递速率(JC)、Rubisco羧化速率(VC)和TPU则明显升高,而且施氮后变化幅度加大;小麦叶片JC/JF(PSⅡ反应中心总电子流速率)和TPU/VC显著增加,经过PSⅡ反应中心的电子流更多地进入碳同化过程,表现较高的光合速率(Pn)。遮荫提高了叶片光化学速率和PSⅡ反应中心总电子流速率(JF),这一作用在低氮叶片尤为突出,但使得J0和V0明显升高,并显著降低JC/JF,所以Pn明显下降。正常光照条件下,增施氮素可提高小麦叶片的JF、JC、VC和TPU,并使高大气CO2浓度下J0和V0较正常大气CO2浓度处理显著降低,有效地提高了植物叶片对光能的利用效率;遮荫后高大气CO2浓度下小麦叶片JC、VC、TPU、JC/JF和TPU/VC显著高于正常大气CO2浓度处理,而且这一变化不受氮素水平的显著调节。因此,氮素在高大气CO2浓度下对小麦叶片光合能量利用的调节因光强而异,正常光照下可显著改善小麦叶片对光合能量的利用状况,而遮荫后这一作用减弱。 相似文献
6.
Xingxue Huang Guolin Zhou Wengang Yang Aihua Wang Zhenhua Hu Chufa Lin Xin Chen 《Journal of plant physiology》2014
To study the mechanisms of drought inhibiting photosynthesis and the role of PAs and ethylene, the photosynthetic rate (Pn), the maximal photochemical efficiency of PSII (Fv/Fm), the intercellular CO2 concentration (Ci), photorespiratory rate (Pr), the amount of chlorophyll (chl), antioxidant enzyme activity, ethylene levels, RuBPC (ribulose-1,5-bisphosphate carboxylase) activity and endogenous polyamine levels of pakchoi were examined, and an inhibitor of S-adenosylmethionine decarboxylase (SAMDC) and an inhibitor of ethylene synthesis and spermidine (Spd) were used to induce the change of endogenous polyamine levels. The results show that drought induced a decrease in Pn and RuBPC activity, an increase in the intercellular CO2 concentration (Ci), but no change in the actual photochemical efficiency of PSII (ΦPSII), and chlorophyll content. In addition, drought caused an increase in the free putrescine (fPut), the ethylene levels, a decrease in the Spd and spermine (Spm) levels, and the PAs/fPut ratio in the leaves. The exogenous application of Spd and amino oxiacetic acid (AOAA, an inhibitor of ethylene synthesis) markedly reversed these drought-induced effects on polyamine, ethylene, Pn, the PAs/fPut ratio and RuBPCase activity in leaves. Methylglyoxal-bis(guanylhydrazone) (MGBG), an inhibitor of SAMDC resulting in the inability of activated cells to synthesize Spd and Spm, exacerbates the negative effects induced by drought. These results suggest that the decrease in Pn is at least partially attributed to the decrease of RuBPC activity under drought stress and that drought inhibits RuBPC activity by decreasing the ratio of PAs/fPut and increasing the release of ethylene. 相似文献
7.
不同天气水稻光合日变化对大气CO2浓度和温度升高的响应——FACE研究 总被引:7,自引:0,他引:7
人类活动导致大气二氧化碳浓度(CO_2)升高、全球气候变暖和光合有效辐射(PAR)降低,影响着绿色作物的光合作用。为了明确高CO_2浓度、高温和低PAR对水稻光合日变化特征的影响,利用中国稻田开放空气CO_2浓度升高系统(free air CO_2enrichment,FACE),以常规粳稻南粳9108为试验材料,设置了环境CO_2和高CO_2浓度(增200μmol/mol)、环境温度和增高温度(增1—2℃)交互的4个处理,从9:00到17:00每隔1h测定了阴天和晴天水稻的光合作用,研究了不同天气对水稻光合日变化对大气CO_2浓度和温度升高的响应。观察到不同天气条件下水稻光合日变化的不同特征,晴天Pn为双峰曲线,发生了光合"午休",阴天未发生。结果表明,高CO_2浓度显著提高了水稻Pn,温度升高有降低水稻Pn趋势,CO_2浓度增加200μmol/mol对水稻光合作用的促进效应远大于增温1—2℃对其的抑制效应。高CO_2浓度显著增加了水稻胞间CO_2浓度(Ci),降低了水稻蒸腾速率(Tr),平均降幅为10.8%—22.0%。高温有降低Ci的趋势,增加了Tr,平均增幅达5.0%—13.5%。晴天比阴天增加了水稻Tr,平均增幅为9.8%—31.2%。CO_2浓度和温度同时升高显著降低了水稻气孔导度(Gs)。这些结果说明CO_2浓度、温度和PAR对水稻水分利用率(WUE)产生综合影响。阴天PAR比晴天平均低53.3%,阴天水稻Pn比晴天显著低,平均降幅达37.1%—72.0%。与对照比较,高CO_2浓度处理,较高PAR(晴天)条件下水稻Pn的增幅(38.6%—58.4%)显著大于较低PAR(阴天)条件下水稻Pn的增幅(21.6%—38.8%),这一现象值得关注和深入探讨。研究结果表明,评估气候变化对水稻生产的影响,需同时考虑未来大气CO_2浓度和温度升高以及PAR下降的因素及其相互作用。 相似文献
8.
Distinct types of carboxysomes were distinguished in Synechococcus PCC 7942: electron-clear, electron-intermediate, carboxysomes with internal electron-clear areas, typical electron-dense and bar-shaped carboxysomes. Immunogold location with antibodies against the Rubisco large subunit showed specific label in all carboxysomes. The positive correlation between electron-density, the density of immunogold label, and the percentage of labeled structures within each type support a model of carboxysome biogenesis whereby electron-clear evolve to electron-intermediate and then to electron-dense carboxysomes by the progressive sequestering of Rubisco molecules. Cells responded to limitation in CO2 supply by increasing carboxysome frequency and the proportion of typical electron-dense carboxysomes, the extent of the response depending on the degree of limitation. The time course of carboxysome expression during transfers between different conditions of CO2 supply indicated that, under our experimental conditions, there were different levels of response, depending on the degree of limitation. The first level occured at atmospheric levels of CO2 and involved changes in the affinity of the CCM and in carboxysome, which occurred simultaneously. More severe limitation of CO2 supply affected carboxysomes exclusively, without further improvement in the affinity of the CCM. 相似文献
9.
G. Heinrich Krause Alexander W. Cheesman Klaus Winter Barbara Krause Aurelio Virgo 《Journal of plant physiology》2013
Global warming and associated increases in the frequency and amplitude of extreme weather events, such as heat waves, may adversely affect tropical rainforest plants via significantly increased tissue temperatures. In this study, the response to two temperature regimes was assessed in seedlings of the neotropical pioneer tree species, Ficus insipida. Plants were cultivated in growth chambers at strongly elevated daytime temperature (39 °C), combined with either close to natural (22 °C) or elevated (32 °C) nighttime temperatures. Under both growth regimes, the critical temperature for irreversible leaf damage, determined by changes in chlorophyll a fluorescence, was approximately 51 °C. This is comparable to values found in F. insipida growing under natural ambient conditions and indicates a limited potential for heat tolerance acclimation of this tropical forest tree species. Yet, under high nighttime temperature, growth was strongly enhanced, accompanied by increased rates of net photosynthetic CO2 uptake and diminished temperature dependence of leaf-level dark respiration, consistent with thermal acclimation of these key physiological parameters. 相似文献
10.
To characterise the stomata of six temperate deciduous tree species, sets of stomatal sensitivities to all the most important environmental factors were measured. To compare the importance of abscisic acid (ABA) in the different stomatal responses, the effect of exogenous ABA on all the stomatal sensitivities was determined.Almost all the stomatal sensitivities: the sensitivity to a decrease in leaf water potential, air humidity, CO2 concentration ([CO2]) and light intensity, and to an increase in [CO2] and light intensity were the highest in the slow-growing species, and the lowest in the fast-growing species. Drought increased the sensitivity to the environmental changes that induce a decrease in the stomatal conductance, and decreased the sensitivity to the changes that induce an increase in this conductance. The sensitivities of the slow-growers were most strongly affected by drought and ABA. Therefore the success of the slow-growers in their ecological niches can be based on the highly sensitive and strictly regulated responses of their stomata. The fast-growers had the highest sensitivity to an increase in leaf water potential and this sensitivity was sharply reduced by drought and ABA. Thus, the dominance of the trees in riparian areas can be based on the ability of their stomata to quickly reach high conductance in well-watered conditions and to efficiently decrease this rate during drought.Stomatal sensitivities to the hydraulic environmental factors (water potentials in plant and air) had higher values in well-watered trees and a more pronounced response to drought than the sensitivities to the photosynthetic environmental factors ([CO2] and light intensity). Thus, the hydraulic factors most likely prevail over the photosynthetic factors in determining stomatal conductance in these species.In response to exogenous ABA, the rates of stomatal closure, following a decrease in air humidity and light intensity, and an increase in [CO2], were accelerated. Stomatal opening following an increase in air humidity and light intensity and a decrease in [CO2] was replaced by slow closing. The rate of stomatal opening following an increase in leaf water potential was reduced. As the sensitivities to changes in light were modified less by the ABA than the other stomatal sensitivities, the prediction of stomatal responses on the basis of the sensitivity to light alone should be excluded in stomatal models. 相似文献
11.
Usue Pérez-López Jon Miranda-ApodacaAlberto Muñoz-Rueda Amaia Mena-Petite 《Journal of plant physiology》2013
As a consequence of the increasing importance of vegetables in the human diet, there is an interest in enhancing both the productivity and quality of vegetables. A number of factors, including plant genotype and environmental growing conditions, can impact the production and quality of vegetables. The objective of this study was to determine whether elevated CO2, salinity, or high light treatments assayed individually, or salinity or high light in combination with elevated CO2, increased biomass production and antioxidant capacity in two lettuce cultivars. Elevated CO2 and its combination with salinity or high light increased biomass production in both cultivars, while high light treatment alone increased production in green-leaf lettuce but not in red-leaf lettuce. On the other hand, elevated CO2 and its combination with salinity or high light increased the antioxidant capacity of both cultivars, while high light treatment alone increased the antioxidant capacity of red-leaf lettuce, but not of green-leaf lettuce. 相似文献
12.
Photosynthetic assimilation of CO2 in plants results in the balance between the photochemical energy developed by light in chloroplasts, and the consumption of that energy by the oxygenation processes, mainly the photorespiration in C3 plants. The analysis of classical biological models shows the difficulties to bring to fore the oxygenation rate due to the photorespiration pathway. As for other parameters, the most important key point is the estimation of the electron transport rate (ETR or J), i.e. the flux of biochemical energy, which is shared between the reductive and oxidative cycles of carbon. The only reliable method to quantify the linear electron flux responsible for the production of reductive energy is to directly measure the O2 evolution by 18O2 labelling and mass spectrometry. The hypothesis that the respective rates of reductive and oxidative cycles of carbon are only determined by the kinetic parameters of Rubisco, the respective concentrations of CO2 and O2 at the Rubisco site and the available electron transport rate, ultimately leads to propose new expressions of biochemical model equations. The modelling of 18O2 and 16O2 unidirectional fluxes in plants shows that a simple model can fit the photosynthetic and photorespiration exchanges for a wide range of environmental conditions. Its originality is to express the carboxylation and the oxygenation as a function of external gas concentrations, by the definition of a plant specificity factor Sp that mimics the internal reactions of Rubisco in plants. The difference between the specificity factors of plant (Sp) and of Rubisco (Sr) is directly related to the conductance values to CO2 transfer between the atmosphere and the Rubisco site. This clearly illustrates that the values and the variation of conductance are much more important, in higher C3 plants, than the small variations of the Rubisco specificity factor. The simple model systematically expresses the reciprocal variations of carboxylation and oxygenation exchanges illustrated by a “mirror effect”. It explains the protective sink effect of photorespiration, e.g. during water stress. The importance of the CO2 compensation point, in classical models, is reduced at the benefit of the crossing points Cx and Ox, concentration values where carboxylation and oxygenation are equal or where the gross O2 uptake is half of the gross O2 evolution. This concept is useful to illustrate the feedback effects of photorespiration in the atmosphere regulation. The constancy of Sp and of Cx for a great variation of P under several irradiance levels shows that the regulation of the conductance maintains constant the internal CO2 and the ratio of photorespiration to photosynthesis (PR/P). The maintenance of the ratio PR/P, in conditions of which PR could be reduced and the carboxylation increased, reinforces the hypothesis of a positive role of photorespiration and its involvement in the plant-atmosphere co-evolution. 相似文献
13.
The accurate assessment of actual tree stem respiration and its relation with temperature plays a considerable role in investigating
the forest carbon cycle. An increasing number of research reports have indicated that tree stem respiration determined with
the commonlyapplied chamber gas exchange measuring system does not follow expectations regarding temperature relationships.
This method is based on the nowadays widely-accepted theory that the respired CO2 in a tree stem would all diffuse outward into the atmosphere. However, it neglects partial CO2 that is dissolved in the xylem sap and is carried away by the transpirational stream. Scientists have started to realize
that the respired CO2 measured with the chamber gas exchange method is only a portion of the total stem respiration (CO2 efflux), while the other portion, which is sometimes very substantial in quantity (thought to occupy maybe 15%–75% of the
total stem respiration), is transported to the upper part of the stem and to the canopy by sap flow. This suggests that the
CO2 produced by respiration is re-allocated within the stem. Accordingly, the change in CO2 efflux could be reflected in the rates of sap flow in addition to its dependence on temperature. Proper methods and instruments
are required to quantify the internal and external CO2 fluxes in the trunk and their interaction with related environmental factors. 相似文献
14.
Elevated CO2 reduces the drought effect on nitrogen metabolism in barley plants during drought and subsequent recovery 总被引:1,自引:0,他引:1
The objective of this study was to determine the response of nitrogen metabolism to drought and recovery upon rewatering in barley (Hordeum vulgare L.) plants under ambient (350 μmol mol−1) and elevated (700 μmol mol−1) CO2 conditions. Barley plants of the cv. Iranis were subjected to drought stress for 9, 13, or 16 days. The effects of drought under each CO2 condition were analysed at the end of each drought period, and recovery was analysed 3 days after rewatering 13-day droughted plants. Soil and plant water status, protein content, maximum (NRmax) and actual (NRact) nitrate reductase, glutamine synthetase (GS), and aminant (NADH-GDH) and deaminant (NAD-GDH) glutamate dehydrogenase activities were analysed. Elevated CO2 concentration led to reduced water consumption, delayed onset of drought stress, and improved plant water status. Moreover, in irrigated plants, elevated CO2 produced marked changes in plant nitrogen metabolism. Nitrate reduction and ammonia assimilation were higher at elevated than at ambient CO2, which in turn yielded higher protein content. Droughted plants showed changes in water status and in foliar nitrogen metabolism. Leaf water potential (Ψw) and nitrogen assimilation rates decreased after the onset of water deprivation. NRact and NRmax activity declined rapidly in response to drought. Similarly, drought decreased GS whereas NAD-GDH rose. Moreover, protein content fell dramatically in parallel with decreased leaf Ψw. In contrast, elevated CO2 reduced the water stress effect on both nitrate reduction and ammonia assimilation coincident with a less-steep decrease in Ψw. On the other hand, Ψw practically reached control levels after 3 days of rewatering. In parallel with the recovery of plant water status, nitrogen metabolism was also restored. Thus, both NRact and NRmax activities were restored to about 75-90% of control levels when water supply was restored; the GS activity reached 80-90% of control values; and GDH activities and protein content were similar to those of control plants. The recovery was always faster and slightly higher in plants grown under elevated CO2 conditions compared to those grown in ambient CO2, but midday Ψw dropped to similar values under both CO2 conditions. The results suggest that elevated CO2 improves nitrogen metabolism in droughted plants by maintaining better water status and enhanced photosynthesis performance, allowing superior nitrate reduction and ammonia assimilation. Ultimately, elevated CO2 mitigates many of the effects of drought on nitrogen metabolism and allows more rapid recovery following water stress. 相似文献
15.
The photosynthetic response of trees to rising CO2 concentrations largely depends on source-sink relations, in addition to differences in responsiveness by species, genotype, and functional group. Previous studies on elevated CO2 responses in trees have either doubled the gas concentration (>700 μmol mol−1) or used single large addition of CO2 (500-600 μmol mol−1). In this study, Gmelina arborea, a fast growing tropical deciduous tree species, was selected to determine the photosynthetic efficiency, growth response and overall source-sink relations under near elevated atmospheric CO2 concentration (460 μmol mol−1). Net photosynthetic rate of Gmelina was ∼30% higher in plants grown in elevated CO2 compared with ambient CO2-grown plants. The elevated CO2 concentration also had significant effect on photochemical and biochemical capacities evidenced by changes in FV/FM, ABS/CSm, ET0/CSm and RuBPcase activity. The study also revealed that elevated CO2 conditions significantly increased absolute growth rate, above ground biomass and carbon sequestration potential in Gmelina which sequestered ∼2100 g tree−1 carbon after 120 days of treatment when compared to ambient CO2-grown plants. Our data indicate that young Gmelina could accumulate significant biomass and escape acclimatory down-regulation of photosynthesis due to high source-sink capacity even with an increase of 100 μmol mol−1 CO2. 相似文献
16.
Salvador Aljazairi Claudia AriasElena Sánchez Gladys LinoSalvador Nogués 《Journal of plant physiology》2014
Wheat is one of the most important cereal food crops in the world today. The productivity and quality of this crop is greatly affected by environmental conditions during grain filling. In this study, we have analyzed two genotypes of durum wheat, Blanqueta and Sula (traditional and a modern wheat respectively) in pre-industrial, current and future [CO2]. Plant growth and physiological parameters were analyzed during anthesis and grain filling in order to study the capacity of these plants to create new sinks and their role during the process of the acclimation of photosynthesis. It was observed that plants underwent photosynthetic acclimation at pre-industrial and future [CO2] (up and down-regulation respectively). However, the modern genotype averts the process of down-regulation by creating a new carbon sink (i.e. the spike). Here, we have shown the essential role that the spike plays as a new sink in order to avert the down-regulation of photosynthesis at future [CO2]. Moreover, we have demonstrated that at future [CO2] the growth response will depend on the ability of plants to develop new sinks or expand existing ones. 相似文献
17.
Gorka Erice Saïd LouahliaJuan José Irigoyen Manuel Sánchez-DíazI. Thami Alami Jean-Christophe Avice 《Environmental and Experimental Botany》2011,72(2):123-130
The predicted worldwide increase in arid areas and water stress episodes will strongly affect crop production. Plants have developed a wide diversity of physiological mechanisms for drought tolerance. A decline in photosynthesis and thus yield production is a common response to drought, as are increases in the water use efficiency of photosynthesis (WUEph) and productivity (WUEp). The aim of our study was to determine the physiological effects (especially WUEph and WUEp) of progressive drought and subsequent recovery in three cultivars adapted to a Mediterranean climate [Tafilalet (TA), Tierra de Campos (TC), and Moapa (MO)], and another representative from an oceanic climate (Europe (EU)). The accuracy of the relationships between WUEph or WUEp and carbon isotope discrimination (Δ 13C) in shoots was also investigated as a function of water stress intensity. Mild drought (7 days of water withholding) decreased the net CO2 exchange (A), leaf conductance to water (g) and transpiration in EU leading to an increased WUEph. Δ 13C was correlated with WUEp but not with WUEph, probably due to a late decrease in g. After moderate drought (14 days), A and g decreased in all cultivars, increasing WUEph. In this period WUEp also increased. Both WUE parameters were correlated with Δ 13C, which may indicate that the g value at the end of moderate water stress was representative of the growing period. After 21 days, TA was the most productive cultivar but under severe drought conditions there was no difference in DM accumulation among cultivars. After the recovery period, leaf area was increased but not total DM, showing that leaves were the most responsive organs to rewatering. Severe water stress did not decrease WUEph or WUEp, and Δ 13C did not increase after recovery. This absence of a response to severe drought may indicate significant effects on the photosynthetic apparatus after 21 days of withholding water. As for mild drought, WUEp but not WUEph was correlated with Δ 13C, supporting the view that WUEp is a more integrative parameter than WUEph. 相似文献
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Shardendu K. Singh Girish Badgujar Vangimalla R. Reddy David H. Fleisher James A. Bunce 《Journal of plant physiology》2013
Nutrients such as phosphorus may exert a major control over plant response to rising atmospheric carbon dioxide concentration (CO2), which is projected to double by the end of the 21st century. Elevated CO2 may overcome the diffusional limitations to photosynthesis posed by stomata and mesophyll and alter the photo-biochemical limitations resulting from phosphorus deficiency. To evaluate these ideas, cotton (Gossypium hirsutum) was grown in controlled environment growth chambers with three levels of phosphate (Pi) supply (0.2, 0.05 and 0.01 mM) and two levels of CO2 concentration (ambient 400 and elevated 800 μmol mol−1) under optimum temperature and irrigation. Phosphate deficiency drastically inhibited photosynthetic characteristics and decreased cotton growth for both CO2 treatments. Under Pi stress, an apparent limitation to the photosynthetic potential was evident by CO2 diffusion through stomata and mesophyll, impairment of photosystem functioning and inhibition of biochemical process including the carboxylation efficiency of ribulose-1,5-bisphosphate carboxylase/oxyganase and the rate of ribulose-1,5-bisphosphate regeneration. The diffusional limitation posed by mesophyll was up to 58% greater than the limitation due to stomatal conductance (gs) under Pi stress. As expected, elevated CO2 reduced these diffusional limitations to photosynthesis across Pi levels; however, it failed to reduce the photo-biochemical limitations to photosynthesis in phosphorus deficient plants. Acclimation/down regulation of photosynthetic capacity was evident under elevated CO2 across Pi treatments. Despite a decrease in phosphorus, nitrogen and chlorophyll concentrations in leaf tissue and reduced stomatal conductance at elevated CO2, the rate of photosynthesis per unit leaf area when measured at the growth CO2 concentration tended to be higher for all except the lowest Pi treatment. Nevertheless, plant biomass increased at elevated CO2 across Pi nutrition with taller plants, increased leaf number and larger leaf area. 相似文献
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The effects of ultraviolet-B (UV-B: 280-320 nm) radiation on the photosynthetic pigments, primary photochemical reactions of thylakoids and the rate of carbon assimilation (Pn) in the cotyledons of clusterbean (Cyamopsis tetragonoloba) seedlings have been examined. The radiation induces an imbalance between the energy absorbed through the photophysical process of photosystem (PS) II and the energy consumed for carbon assimilation. Decline in the primary photochemistry of PS II induced by UV-B in the background of relatively stable Pn, has been implicated in the creation of the energy imbalance. The radiation induced damage of PS II hinders the flow of electron from QA to QB resulting in a loss in the redox homeostasis between the QA to QB leading to an accumulation of QA−. The accumulation of QA− generates an excitation pressure that diminishes the PS II-mediated O2 evolution, maximal photochemical potential (Fv/Fm) and PS II quantum yield (ΦPS II). While UV-B radiation inactivates the carotenoid-mediated protective mechanisms, the accumulation of flavonoids seems to have a small role in protecting the photosynthetic apparatus from UV-B onslaught. The failure of protective mechanisms makes PS II further vulnerable to the radiation and facilitates the accumulation of malondialdehyde (MDA) indicating the involvement of reactive oxygen species (ROS) metabolism in UV-B-induced damage of photosynthetic apparatus of clusterbean cotyledons. 相似文献